The disclosure relates to electronic signal processing. More particularly, the disclosure relates to a harmonic reject RF receiver, harmonic reject receiver architecture, and harmonic reject mixers.
RF communication systems often provide numerous frequency division multiplexed channels distributed over a predetermined operating band. A receiver can typically be configured to tune to a desired channel to receive the information provided on that channel.
In many communication systems, the operating band is a relatively narrow band. That is, the operating band typically does not occupy greater than an octave. However, in some communication systems, such as television, the operating frequency band may include hundreds of channels occupying several octaves.
Such a wide operating bandwidth can present particular problems not experienced in other systems having sub-octave operating frequency bands. For example, a wide operating bandwidth may include multiple in band interferers. The undesired channels in a television operating band can appear as interferers to the desired channel. The undesired channels can be at substantially the same power level, or even at a greater power level, than the power level of the desired channel.
A receiver typically filters or otherwise attenuates undesired channels and other interference sources. However, some interferers may contribute to in band interference due to operation of the receiver, such that filtering is ineffective. In particular, a receiver may unintentionally frequency convert the harmonics of the desired input signal to the same frequency band that is converts the desired signal.
Because the interferer can frequency convert to an in band interference signal, it is not possible to filter out the interference. Additionally, the input operating frequency band may span multiple octaves and may include the harmonics. The receiver may not be able to sufficiently eliminate the effects of the harmonic interferers by filtering the input signal.